Half of all physicians practicing in the United States obtain medical liability coverage from a member of the Physician Insurers Association of America (PLAA). Colorado's PIAA, the Copic Insurance Company, insures 75% of the state's primary care physicians. A leading cause of PIAA's liability claims arises from physicians' failure to detect cancer in a timely fashion. Together, Copic and investigators from the AMC Cancer Research Center will apply methods from their prior research to study cancer prevention and early detection in primary care practices throughout Colorado, a state with a diverse, multi-ethnic population. The following research aims will be addressed simultaneously: 1) to conduct a randomized, controlled trial to determine the extent to which Copic-initiated interventions, differing in intensity and cost, will affect the option and maintenance of cancer prevention and early detection procedures by primary care physicians; 2) to determine whether the process of being evaluated by Copic is sufficient to affect he adoption of cancer prevention and early detection procedures; and 3) to determine the extent which changes in early cancer detection diffuse to Copic practices not receiving an intervention; and if diffusion occurs, to identify factors that explain it. The main dependent variable is the increase in physicians' conformity to NCI endorsed guidelines for the prevention and early detection of breast, cervical, skin, and prostate cancer. Physicians will be stratified by practice location (urban/nonurban) and readiness to change (+,-). Then, one physician from each of 112 practices will be randomly assigned to either a control or one of three intervention groups: Self-instruction; Self-instruction + regional meeting and office visit; Self-instruction + regional meeting, office visit, and continuing consultation visits (intervention study). To assess the impact of Copic's medical record reviews and patient exit- interviews, 56 additional physicians will be randomly assigned either to have both beginning and endpoint assessment or to have just endpoint assessment (baseline impact study). A descriptive study will examine the extent to which physicians not receiving an intervention increase conformity with guidelines by at least 10% from beginning to endpoint two years later (diffusion study). Potential predictors of diffusion include level of readiness of office staff, distance from a mammography screening site, ethnic composition and insurance coverage of the patients, etc. Cost effectiveness analyses will compare program costs with outcomes achieved.